Cleaning sheet, conveying member using the same, and substrate processing equipment cleaning method using them

ABSTRACT

A cleaning sheet for cleaning foreign matters away from the interior of the substrate processing equipment is provided. The cleaning sheet includes a cleaning layer having substantially no tackiness and having a tensile modulus of not lower than 0.98 N/mm 2  as determined according to JIS K7127. Alternatively, the cleaning sheet includes a cleaning layer having a Vickers hardness of not lower than 10.

TECHNICAL FIELD

[0001] The present invention relates to a sheet for cleaning variousequipments. More particularly, the present invention relates to acleaning sheet for a substrate processing equipment which is apt to beeasily damaged by foreign matters such as equipment for producing orinspecting semiconductor, flat panel display, printed circuit board,etc., a conveying member comprising same, and a method for cleaning asubstrate processing equipment using same.

BACKGROUND ART

[0002] Various substrate processing equipments are adapted to conveyvarious conveying systems and substrates while allowing them to come inphysical contact with each other. During this operation, when foreignmatters are adhered to these substrates and conveying systems, thesubsequent substrates can be successively contaminated. This, it isnecessary that the equipment be regularly suspended for cleaningpurpose. This causes the drop of operating efficiency or requires muchlabor to disadvantage. In order to solve these problems, a method hasbeen proposed which comprises conveying a substrate having an adhesivematerial attached thereto to clean foreign matters away from theinterior of the substrate processing equipment (as in UnexaminedJapanese Patent Publication 10-154686).

[0003] The method which comprises conveying a substrate having anadhesive material attached thereto to clean foreign matters away fromthe interior of the substrate processing equipment is an effectivemethod for overcoming the foregoing difficulties. However, this methodis disadvantageous in that the adhesive material and the contact area ofthe equipment adhere to each other too strongly to peeled off eachother, making it impossible to assure the complete conveyance of thesubstrate.

DISCLOSURE OF INVENTION

[0004] In light of these circumstances, an object of the invention is toprovide a cleaning sheet which can certainly convey substrates to theinterior of a substrate processing equipment as well as remove foreignmatters attached to the interior of the equipment easily and certainly.

[0005] The inventors made extensive studies to accomplish the foregoingobject. As a result, it was found that foreign matters can be simply andcertainly removed without causing the foregoing problems by conveying asheet having a cleaning layer or a substrate having such a sheet fixedthereto to clean foreign matters away from the interior of a substrateprocessing equipment wherein the cleaning layer has substantially notackiness and a tensile modulus of not lower than a specific value orhas surface free energy of less than a specific value or Vickershardness of not lower than a specific value.

[0006] In other words, the present invention provides a cleaning sheetcomprising a cleaning layer having substantially no tackiness and havinga tensile modulus of not lower than 0.98N/mm² as determined according toJIS K7127. The cleaning layer may be provided on a base material, or maybe provided on one side of the base material and an ordinary adhesivelayer may be provided on the other. The cleaning layer preferably hassubstantially no tackiness and substantially no electrical conductivity.The cleaning layer preferably exhibits a surface free energy of lessthan 30 mJ/m².

[0007] The present invention also provides a cleaning sheet comprising acleaning layer having a Vickers hardness of not lower than 10. Thecleaning layer may be provided on a base material, or may be provided onone side of a base material and an ordinary adhesive layer may beprovided on the other.

[0008] The aforementioned cleansing sheets may be further modified fromother aspects.

[0009] Features and advantages of the invention will be evident from thefollowing detailed description of the preferred embodiments.

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] In the cleaning sheet according to the invention, the cleaninglayer (hereinafter, including forms such as single cleaning sheet,laminated sheet and sheet laminated with base material) needs to havesubstantially no tackiness and have a tensile modulus of not lower than0.98 N/mm², preferably from 0.98 to 4,900 N/mm², more preferably from9.8 to 3,000 N/mm² as determined according to JIS K7127. In accordancewith the invention, the tensile modulus of the cleaning layer isdesigned to fall within the above defined specific range, making itpossible to remove foreign matters without causing any troubles inconveyance. When the tensile modulus of the cleaning layer falls below0.98 N/mm², the cleaning layer becomes adhesive and thus can adhere tothe interior area of the equipment to be cleaned during conveyance,causing troubles in conveyance.

[0011] The cleaning layer exhibits a 180° peel adhesion of not greaterthan 0.20 N/10 mm, preferably from 0.01 to 0.1 N/10 mm with respect tosilicon wafer (mirror surface). When the peel adhesion of the cleaninglayer exceeds 0.20 N/10 mm, the cleaning layer adheres to the interiorarea of the equipment to be cleaned, causing troubles in conveyance.

[0012] It is preferred that the cleaning layer in the cleaning sheet ofthe invention be made of a layer having substantially no tackiness andsubstantially no electrical conductivity. In the invention, the cleaningsheet can be designed such that the cleaning layer has substantially notackiness and substantially no electrical conductivity, making itpossible to remove foreign matters by an electrostatic attractionwithout causing any trouble in conveyance.

[0013] The cleaning layer preferably exhibits a surface resistivity ofnot lower than 1×10¹³ Ω/□, more preferably not lower than 1×10¹⁴ Ω/□. Bydesigning the cleaning sheet such that the surface resistivity of thecleaning layer is predetermined to be not lower than such a specificvalue to make the cleaning layer insulating as much as possible, anelectrostatic effect of catching and adsorbing foreign matters can beexerted. Accordingly, when the surface resistivity of the cleaning layerfalls below 1×10¹³ Ω/□, the electrostatic effect of catching andadsorbing foreign matters can be impaired.

[0014] The cleaning layer is not specifically limited in its materialand structure so far as it has substantially no tackiness andsubstantially no electrical conductivity. Examples of such a materialinclude a film of plastic such as polyethylene, polyethyleneterephthalate, acetyl cellulose, polycarbonate, polypropylene,polyamide, polyimide and polycarbodimide, and a material havingsubstantially no tackiness obtained by hardening a hardenable adhesive.

[0015] The cleaning layer in the cleaning sheet of the inventionpreferably exhibits a surface free energy of less than 30 mJ/m²,preferably from 25 to 15 mJ/m². The term “surface free energy ofcleaning layer (solid)” as used herein is meant to indicate a valuedetermined by solving as a simultaneous linear equation two equationsobtained by substituting measurements of contact angle of the surface ofthe cleaning layer with respect to water and methylene iodide and thesurface free energy of these liquids used in the measurement of contactangle (known from literatures) in Young's equation and the followingequation (1) derived from extended Fowkes' equation.

(1+cos θ)γ_(L)=2{square root}{square root over ((γ_(s) ^(d)γ_(L)^(d)))}+2{square root}{square root over ((γ_(s) ^(p)γ_(L) ^(p)))}  (1)

[0016] where θ represents a contact angle; γ_(L) represents the surfacefree energy of the liquid used in the measurement of contact angle;γ_(L) ^(d) represents the dispersion force component in γ_(L); γ_(L)^(p) represents the polar force component in γ_(L); γ_(s) ^(d)represents the dispersion force component in the surface free energy ofsolid; and γ^(s) _(p) represents the polar force component in thesurface free energy of solid.

[0017] The cleaning sheet is preferably designed such that the surfaceof the cleaning layer exhibits a contact angle of more than 90 degrees,more preferably more than 100 degrees with respect to water. In theinvention, by designing the cleaning layer such that it exhibits asurface free energy and a contact angle with respect to water fallingwithin the range defined above, an effect of conveying the cleaningsheet certainly without causing the cleaning layer to adhere firmly tothe position to be cleaned during conveyance can be exerted.

[0018] The cleaning layer in the second cleaning sheet of the inventionneeds to have a Vickers hardness of not lower than 10, preferably from20 to 500. The term “Vickers hardness” as used herein is meant toindicate a value obtained by dividing a predetermined load applied to adiamond indenter according to JIS Z2244 by the surface area of theresulting dent. In the invention, by designing the cleaning sheet suchthat the Vickers hardness of the cleaning layer is not lower than thepredetermined value, an effect of conveying the cleaning sheet withoutcausing the cleaning layer to come in close contact with the position tobe cleaned during conveyance can be exerted.

[0019] The cleaning layer in the second cleaning sheet of the inventionpreferably exhibits a surface free energy of less than 30 mJ/m², morepreferably from 15 to 25 mJ/m². The cleaning layer exhibits a surfacecontact angle of greater than 90 degrees, preferably greater than 100degrees with respect to water. In the invention, by designing thecleaning layer such that it exhibits a surface free energy and a contactangle with respect to water falling within the range defined above, aneffect of conveying the cleaning sheet certainly without causing thecleaning layer to adhere firmly to the position to be cleaned duringconveyance can be exerted.

[0020] The foregoing cleaning layer is not specifically limited in itsmaterial, etc. so far as it has a tensile modulus or Vickers hardness ofnot lower than the above defined value and has substantially notackiness. In practice, however, there may be preferably used a materialwhich can undergo accelerated crosslinking reaction or curing by anactive energy such as ultraviolet light and heat to exhibit an enhancedtensile modulus.

[0021] The foregoing cleaning layer is preferably made of a materialobtained by subjecting a pressure-sensitive adhesive polymer containingat least a compound having one or more unsaturated double bonds permolecule and a polymerization initiator to polymerization curingreaction with an active energy so that the tackiness thereofsubstantially disappears. A such a pressure-sensitive adhesive polymerthere may be used an acrylic polymer comprising as a main monomer a(meth)acrylic acid and/or (meth)acrylic acid ester selected from thegroup consisting of acrylic acid, acrylic acid ester, methacrylic acidand methacrylic acid ester. When the synthesis of the acrylic polymercan be accomplished by using a compound having two or more unsaturateddouble bonds per molecule or chemically bonding a compound havingunsaturated double bonds per molecule to the acrylic polymer thussynthesized through the reaction of functional groups so thatunsaturated double bonds are introduced into the molecule of acrylicpolymer, the resulting polymer itself can participate in thepolymerization curing reaction by an active energy.

[0022] The compound having one or more unsaturated double bonds permolecule (hereinafter referred to as “polymerizable unsaturatedcompound”) preferably is nonvolatile low molecular compound having aweight-average molecular weight of not higher than 10,000. Inparticular, the polymerizable unsaturated compound preferably has amolecular weight of not higher than 5,000 so that the adhesive layer canbe three-dimensionally networked more efficiently during curing.

[0023] The polymerizable unsaturated compound also preferably is anonvolatile low molecular compound having a weight-average molecularweight of not higher than 10,000. In particular, the polymerizableunsaturated compound preferably has a molecular weight of not higherthan 5,000 so that the cleaning layer can be three-dimensionallynetworked more efficiently during curing. Examples of such apolymerizable compound include phenoxy polyethyleneglycol(meth)acrylate, ε-caprolactone (meth)acrylate, polyethylene glycoldi(meth)acrylate, polypropylene glycol di(meth)acrylate,trimethylolpropane tri(meth)acrylate, dipentaerythritolhexa(meth)acrylate, urethane (meth)acrylate, epoxy(meth)acrylate, andoligoester (meth)acrylate. These polymerizable compounds maybe usedsingly or in combination of two or more thereof.

[0024] As the polymerization initiator to be incorporated in thecleaning layer there may be used any known material without anyrestriction. If heat is used as an active energy, a heat polymerizationinitiator such as benzoyl peroxide and azobisisobutyronitrile may beused. If light is used as an active energy, a photopolymerizationinitiator such as benzoyl, benzoin ethyl ether, dibenzyl,isopropylbenzoin ether, benzophenone, Michler's ketonechlorothioxanthone, dodecyl thioxanthone, dimethyl thioxanthone,acetophenone diethyl ketal, benzyl dimethyl ketal, α-hydroxy cyclohexylphenyl ketone, 2-hydroxy dimethyl phenyl propane and2,2-dimethoxy-2-phenyl acetophenone may be used.

[0025] The thickness of the cleaning layer is not specifically limited.In practice, however, it is normally from about 5 to 100 μm.

[0026] The present invention also provides a cleaning sheet comprisingthe foregoing specific cleaning layer provided on one side of a basematerial and an ordinary adhesive layer provided on the other. Theadhesive layer to be provided on the other side of the base material isnot specifically limited in its material so far as it can exhibit adesired sticking function. An ordinary adhesive (e.g., acrylic adhesive,rubber-based adhesive) may be used.

[0027] In this arrangement, the cleaning sheet can be stuck to varioussubstrates or other conveying members such as tape and sheet with anordinary adhesive layer so that it can be conveyed to the interior ofthe equipment as a conveying member with a cleaning function to come incontact with the position to be cleaned, making it possible to clean theequipment.

[0028] In the case where the substrate is peeled off the adhesive layerafter cleaning to re-use the foregoing conveying member such assubstrate, the adhesive layer may have a 180° peel adhesion of from 0.01to 0.98 N/10 mm, particularly from about 0.01 to 0.5 N/10 mm withrespect to silicon wafer (mirror surface), making it possible to preventthe substrate from being peeled off the adhesive layer and easily peelthe substrate after cleaning.

[0029] The base material on which the cleaning layer is provided is notspecifically limited. As such a base material there may be used a filmof a plastic such as polyethylene, polyethylene terephthalate, acetylcellulose, polycarbonate, polypropylene and polyamide. The thickness ofthe base material is normally from about 10 to 100 μm.

[0030] The conveying member to which the cleaning sheet is stuck is notspecifically limited. In practice, however, a substrate such assemiconductor wafer, substrate for flat panel display (e.g., LCD, PDP)and substrate for compact disk and MR head may be used.

[0031] The present invention further provides a member for cleaningvarious conduction inspection equipments, a method for cleaning aconduction inspection equipment using same, and a member and method forcleaning a conduction inspection equipment which is apt to be easilydamaged by foreign matters.

[0032] Various conduction inspection equipments for use in theproduction of semiconductor inspect electrical conduction by bringingthe contact point on the inspection equipment side (e.g., contact pin ofIC socket) into contact with the terminal on the product side (e.g.,terminal of semiconductor). During this procedure, when the inspectionis repeated, the contact of IC terminal with the contact pin isrepeated. As a result, the contact pin shaves the material on ICterminal side (e.g., aluminum, solder). The resulting foreign mattersare attached to the contact pin side. Further, aluminum and solder whichhave thus been attached to the contact pin side are oxidized, causingdefects due to insulation. In worst case, the electrical conductivity tobe inspected can be lowered. In order to remove these foreign mattersfrom the contact pin, a polyethylene terephthalate film coated withalumina particles or a member having abrasive grains incorporated in arubber-based resin such as silicone (hereinafter referred to as “contactpin cleaner”) is used. However, with the recent trend toward thereduction of the thickness of wafer and increase of the length of waferin the process for the production of semiconductor, wafer can be damagedmore by foreign matters on the inspection table (chuck table) andchucking error can occur more. Thus, some countermeasure needs to betaken to remove foreign matters from the chuck table. To this end, it isnecessary that the operation of the conduction inspection equipment beregularly suspended to clean the chuck table, there by removing foreignmatters therefrom. This causes the drop of operating efficiency orrequires much labor to disadvantage.

[0033] Under these circumstances, another object of the invention is toprovide a cleaning member and cleaning method which can clean thecontact pin in the conduction inspection equipment as well as reduce theamount of foreign matters attached to the chuck table and conveying arm.

[0034] The inventors made extensive studies to accomplish the foregoingobject. As a result, it was found that by conveying a cleaning membercomprising a member for removing foreign matters attached to theconduction inspection contact pin in a conduction inspection equipment(hereinafter referred to as “contact pin cleaner”) and a cleaning layerprovided on one side of the contact pin cleaner for removing foreignmatters attached to the contact area of the equipment with which thecontact pin cleaner comes in contact (chuck table), the contact pin canbe cleaned while removing foreign matters attached to the chuck table inthe inspection equipment. It was also found that by predetermining thefriction coefficient of the cleaning layer to be not lower than aspecific value, the cleaning sheet can be certainly conveyed through theinterior of the inspection equipment while simply reducing the amount offoreign matters. Thus, the present invention has been worked out.

[0035] In other words, the present invention also provides a cleaningmember for conduction inspection equipment comprising a member forremoving foreign matters attached to the conduction inspection contactpin in a conduction inspection equipment (hereinafter referred to as“contact pin cleaner”) and a cleaning layer provided on one side of thecontact pin cleaner for removing foreign matters attached to the contactarea of the equipment with which the contact pin cleaner comes incontact.

[0036] The present invention further provides a cleaning member forconduction inspection equipment comprising a member provided on one sideof a conveying member for removing foreign matters attached to theconduction inspection contact pin of the conduction inspection equipment(hereinafter referred to as “contact pin cleaner”) and the foregoingcleaning sheet provided on the other for removing foreign mattersattached to the contact area of an equipment with which said contact pincleaner comes in contact.

[0037] The cleaning layer in the cleaning member of the invention is notspecifically limited so far as it can be certainly conveyed through theinterior of the inspection equipment as well as reduce the amount offoreign matters simply. In practice, however, the friction coefficientof the cleaning layer is preferably not lower than 1.0, more preferablyfrom 1.2 to 1.8 from the standpoint of dust-removing properties andconveying properties. When the friction coefficient of the cleaninglayer falls below 1.0, there is a fear that foreign matters on the chucktable cannot be certainly attached to the cleaning layer. On thecontrary, when the friction coefficient of the cleaning layer exceedsthe above defined range, there is a fear that the cleaning sheet canfail to be conveyed. In the present invention, the friction coefficient(μ) of the cleaning layer is determined by measuring the frictioncoefficient (F) developed when a stainless steel plate (50 mm×50 mm flatplate) is allowed to slide along the surface of the cleaning layer bymeans of a universal testing machine, and then substituting thismeasurement and the vertical load (W) applied to the steel plate duringthis process in the following equation (2). This represents a dynamicfriction coefficient.

μ=F/W  (2)

[0038] wherein μ represents a dynamic friction coefficient; F representsa frictional resistance (N); and W represents the vertical load (N)applied to steel plate.

[0039] The cleaning layer exhibits a tensile modulus of not higher than2,000N/mm², preferably greater than 1 N/mm². When the tensile modulus ofthe cleaning layer exceeds 2,000 N/mm², there is a fear that foreignmatters on the chuck table cannot be certainly attached to the cleaninglayer. On the contrary, when the tensile modulus of the cleaning layerfalls below 1 N/mm², there is a fear that the cleaning sheet can fail tobe conveyed. In the invention, by predetermining the frictioncoefficient and the tensile modulus of the cleaning layer to be withinthe above defined range, the cleaning layer has substantially notackiness during the conveyance of the cleaning sheet or the like,making it possible to exert an effect of conveying the cleaning sheetwithout causing the cleaning layer to adhere firmly to the position tobe cleaned.

[0040] The contact pin cleaner to be used in the invention is notspecifically limited in its material, shape and other factors. A widerange of materials can be used. For example, a film of a plastic such aspolyethylene, polyethylene terephthalate, acetyl cellulose,polycarbonate, polypropylene, polyamide, polyimide and polycarbodimide,a rubber-based resin such as silicone or a substrate (backing) such asnon-woven fabric coated with an abrasive grain such as particulatealumina, silicon carbide and chromium oxide may be used, but the presentinvention should not be construed as being limited thereto. The shape ofthe contact pin cleaner can be properly determined depending on theshape of socket and IC to be cleaned such as silicon wafer and IC chipand the kind of the equipment.

[0041] In this arrangement, the cleaning sheet can be conveyed to theinterior of the equipment while being stuck to the contact pin cleanerfor cleaning the contact pin on the non-cleaning side thereof orconveying member such as various substrates with a cleaning functionwith an ordinary adhesive layer to form a conveying member so that itcomes in contact with the chuck table for cleaning.

[0042] The conveying member on which the cleaning layer is provided isnot specifically limited. In practice, however, there may be used asemiconductor wafer, substrate for flat panel display such as LCD andPDP, substrate for compact disk and MR head, or a film of a plastic suchas polyethylene, polyethylene terephthalate, acetyl cellulose,polycarbonate, polypropylene, polyamide, polyimide and polycarbodimide.

[0043] The present invention further provides a process for theproduction of a conveying member with a cleaning function for varioussubstrate processing equipments, e.g., a process for the production of aconveying member with a cleaning function which is apt to be easilydamaged by foreign matters such as equipment for producing or inspectingsemiconductor, flat panel display, printed circuit board, etc.

[0044] The foregoing process for the production of a conveying memberwith a cleaning function (hereinafter referred to as “cleaning member”)is disadvantageous in that when a cleaning member produced by laminatinga conveying member such as substrate with a cleaning sheet having ashape greater than that of the conveying member is cut on the cleaningsheet along the profile of the conveying member (hereinafter thisprocess will be referred to as “direct cutting process”), cutting wastesare produced from the cleaning layer during cutting and attached to thecleaning member to disadvantage. In the case where a cleaning sheet forlabel which has been previously processed into the shape of theconveying member is laminated with a conveying member to produce acleaning member, the production of cutting wastes during the working oflabel can be inhibited as compared with direct cutting process. However,the cutting of sheet for label must be previously conducted, adding tothe number of working steps required, complicating the process for theproduction of cleaning member and hence deteriorating the operatingefficiency.

[0045] Under these circumstances, a further object of the invention isto provide a process for the preparation of a cleaning member which cancertainly be conveyed through the interior of the substrate processingequipment, can certainly and simply remove foreign matters attached tothe interior of the substrate processing equipment and produces nocutting wastes during the cutting of sheet by direct cutting process.

[0046] The inventors made extensive studies to accomplish the foregoingobject. As a result, it was found that by making a cleaning layer of anadhesive which undergoes polymerization curing when acted upon by anactive energy and conducting the polymerization curing reaction of thecleaning layer after cutting the cleaning sheet into the shape of theconveying member in the process for the production of a cleaning memberwhich comprises laminating a conveying member such as substrate with acleaning sheet wherein the production of the cleaning member isaccomplished by direct cutting process, a cleaning member which cansimply and certainly peel foreign matters can be produced withoutcausing the foregoing problems. Thus, the present invention has beenworked out.

[0047] In other words, the present invention further provides a processfor the preparation of a conveying member with a cleaning function whichcomprises laminating a cleaning sheet having a cleaning layer made of anadhesive which undergoes polymerization curing when acted upon by anactive energy provided on one side of a base material and an ordinaryadhesive layer provided on the other with a conveying member with anordinary adhesive layer interposed therebetween in such an arrangementthat the shape of the cleaning sheet is greater than that of theconveying member, and then cutting said cleaning sheet along the profileof the conveying member, characterized in that the cleaning layerundergoes polymerization curing reaction after the cutting of thecleaning sheet along the profile of the conveying member.

[0048] In the process for the preparation of a cleaning member accordingto the invention, it is necessary that the cleaning layer be made of anadhesive which undergoes polymerization curing with an active energy andthe polymerization curing be conducted after sheet cutting. This isbecause when the cleaning layer is allowed to undergo polymerizationcuring before sheet cutting, it undergoes crosslinking to have a higherelastic modulus, causing the production of a large amount of cuttingwastes which are attached to the cleaning member or the equipment. Inorder to prevent the production of cutting wastes from the cleaninglayer during sheet cutting, it is preferred that the tensile modulus ofthe cleaning layer be not higher than 1 N/mm², preferably not higherthan 0.1 N/mm² as determined by a testing method according to JIS K7127.By predetermining the tensile modulus of the cleaning layer to be nothigher than the foregoing specific range, the production of cuttingwastes from the cleaning layer during sheet cutting can be prevented,making it possible to prepare a cleaning member free of cutting wastesby direct cutting process. Further, a cleaning layer made of an adhesivewhich undergoes polymerization curing can undergo polymerization curingafter sheet cutting to have substantially no tackiness, making itpossible to provide a cleaning member which can be certainly conveyedwithout firmly adhering to the contact area of the equipment.

[0049] In the present invention, the cleaning layer after sheet cuttingexhibits a tensile modulus of not lower than 10 N/mm², preferably from10 to 2,000 N/mm² due to the acceleration of crosslinking reaction orcuring by an active energy. When the tensile modulus of the cleaninglayer exceeds 2,000 N/mm², the capacity of removing foreign matters fromthe conveying system is deteriorated. On the contrary, when the tensilemodulus of the cleaning layer falls below 10 N/mm², the cleaning layeradheres to the interior area of the equipment to be cleaned duringconveyance, causing troubles in conveyance.

[0050] The preparation of the cleaning member according to the inventioninvolves the use of a cleaning sheet comprising the foregoing specificadhesive layer provided as a cleaning layer on one side of a basematerial and an ordinary adhesive layer provided on the other, saidcleaning layer being in uncured form.

[0051] The present invention will be further described in the followingexamples, but the present invention should not be construed as beinglimited thereto. The term “parts” as used hereinafter is meant toindicate parts by weight.

EXAMPLE 1

[0052] To 100 parts of an acrylic polymer (weight-average molecularweight: 700,000) obtained from a monomer mixture comprising 75 parts of2-ethylhexyl acrylate, 20 parts of methyl acrylate and 5 parts ofacrylic acid were added 50 parts of a polyethylene glycoldimethacrylate, 50 parts of urethane acrylate, 3 parts of benzyldimethyl ketal and 3 parts of diphenylmethane diisocyanate. The mixturewas then uniformly stirred to obtain a solution of an ultraviolet-curingadhesive.

[0053] The adhesive which had been irradiated with ultraviolet lighthaving a central wavelength of 365 nm in an integrated dose of 1,000mJ/cm² to undergo curing exhibited a tensile modulus of 49 N/mm². Themeasurement of tensile was carried out by a testing method according toJIS K7127.

[0054] Separately, an adhesive solution obtained in the same manner asmentioned above except that the foregoing adhesive was free of benzyldimethyl ketal was applied to the peel surface of a polyester peelablefilm having a thickness of 38 μm and a width of 250 mm to a drythickness of 10 μm to provide an ordinary adhesive layer thereon.Subsequently, the foregoing ultraviolet-curing adhesive solution wasapplied to the peel surface of a polyester peelable film having athickness of 38 μm to a dry thickness of 40 μm to provide a cleaninglayer thereon. The two polyester peelable films were then laminated witheach other in such an arrangement that the cleaning layer and theordinary adhesive layer were opposed to each other.

[0055] The resulting sheet was then irradiated with ultraviolet lighthaving a central wavelength of 365 nm in an integrated dose of 1,000mJ/cm² to obtain a cleaning sheet according to the invention. Thesurface of the cleaning layer had substantially no tackiness.

[0056] The cleaning layer was measured for surface resistivity at atemperature of 23° C. and a relative humidity of 60% by means of a TypeMCP-UP450 surface resistivity meter produced by Mitsubishi ChemicalCorporation. As a result, the reading was greater than 9.99×10¹³ Ω/□,making the measurement impossible.

[0057] The peelable film was then peeled off the cleaning sheet on theordinary adhesive layer side thereof. The cleaning sheet was then stuckto the back side (mirror surface) of an 8 inch silicon wafer to preparea conveying cleaning wafer with a cleaning function.

[0058] Separately, two wafer stages were removed from a substrateprocessing equipment, and then measured for the presence of foreignmatters having a size of not smaller than 0.3 μm by means of a lasertype foreign matter analyzer. As a result, foreign matters having a sizeof not smaller than 0.3 μm were found on an area having an 8 inch wafersize in a number of 18,000 on one of the two wafer stages and 17,000 onthe other.

[0059] Subsequently, the peelable film was peeled off the foregoingconveying cleaning wafer on the cleaning layer side thereof. Theconveying cleaning wafer was then conveyed to the interior of thesubstrate processing equipment having the wafer stage having 18,000foreign matters attached thereto. As a result, the conveyance of theconveying cleaning wafer was conducted without any troubles. Thereafter,the wafer stage was removed, and then measured for the presence offoreign matters having a size of not smaller than 0.3 μm by means of alaser type foreign matter analyzer. As a result, foreign matters havinga size of not smaller than 0.3 μm were found on an area having an 8 inchwafer size in a number of 4,000, demonstrating that ¾ or more of theforeign matters which had been attached before cleaning had beenremoved.

COMPARATIVE EXAMPLE 1

[0060] The cleaning layer in a cleaning sheet prepared in the samemanner as in Example 1 except that the amount of benzyl dimethyl ketalwas 0.05 parts had tackiness. The cleaning layer was then measured fortensile modulus. The results were 0.5 N/mm².

[0061] It was tried to convey a conveying cleaning wafer prepared fromthe foregoing cleaning sheet in the same manner as in Example 1 throughthe interior of the substrate processing equipment. However, theconveying cleaning wafer adhered to the conveying arm and thus could notbe conveyed.

EXAMPLE 2

[0062] To 100 parts of an acrylic polymer (weight-average molecularweight: 700,000) obtained from a monomer mixture comprising 75 parts of2-ethylhexyl acrylate, 20 parts of methyl acrylate and 5 parts ofacrylic acid were added 50 parts of a polyethylene glycoldimethacrylate, 50 parts of urethane acrylate, 3 parts of benzyldimethyl ketal and 3 parts of diphenylmethane diisocyanate. The mixturewas then uniformly stirred to obtain a solution of an ultraviolet-curingadhesive.

[0063] Separately, an adhesive solution obtained in the same manner asmentioned above except that the foregoing adhesive was free of benzyldimethyl ketal was applied to one side of a polyester peelable filmhaving a thickness of 25 μm and a width of 250 mm to a dry thickness of10 μm to provide an ordinary adhesive layer thereon. A polyesterpeelable film having a thickness of 38 μm was then stuck to the surfaceof the ordinary adhesive layer. The foregoing ultraviolet-curingadhesive solution was applied to the other side of the base materialfilm to a dry thickness of 40 μm to provide an adhesive layer as acleaning layer thereon. A similar peelable film was then stuck to thesurface of the cleaning layer.

[0064] The resulting sheet was then irradiated with ultraviolet lighthaving a central wavelength of 365 nm in an integrated dose of 1,000mJ/cm² to obtain a cleaning sheet according to the invention. Theadhesive layer as a cleaning layer in the cleaning sheet which had beencured by ultraviolet light exhibited a tensile modulus of 49 N/mm². Themeasurement of tensile modulus was carried out by a testing methodaccording to JIS K7127.

[0065] The adhesive layer on the cleaning layer side was stuck to themirror surface of a silicon wafer at a width of 10 mm, and then measuredfor 180° peel adhesion with respect to silicon wafer according to JISZ0237. The results were 0.08 N/10 mm.

[0066] The peelable film was then peeled off the cleaning sheet on theadhesive layer side thereof. The cleaning sheet was then stuck to theback side (mirror surface) of an 8 inch silicon wafer to prepare aconveying cleaning wafer with a cleaning function.

[0067] Separately, two wafer stages were removed from a substrateprocessing equipment, and then measured for the presence of foreignmatters having a size of not smaller than 0.3 μm by means of a lasertype foreign matter analyzer. As a result, foreign matters having a sizeof not smaller than 0.3 μm were found on an area having an 8 inch wafersize in a number of 25,000 on one of the two wafer stages and 22,000 onthe other.

[0068] Subsequently, the peelable film was peeled off the foregoingconveying cleaning wafer on the cleaning layer side thereof. Theconveying cleaning wafer was then conveyed to the interior of thesubstrate processing equipment having the wafer stage having 25, 000foreign matters attached thereto. As a result, the conveyance of theconveying cleaning wafer was conducted without any troubles. Thereafter,the wafer stage was removed, and then measured for the presence offoreign matters having a size of not smaller than 0.3 μm by means of alaser type foreign matter analyzer. As a result, foreign matters havinga size of not smaller than 0.3 μm were found on an area having an 8 inchwafer size in a number of 6,200, demonstrating that ¾ or more of theforeign matters which had been attached before cleaning had beenremoved.

COMPARATIVE EXAMPLE 2

[0069] A cleaning sheet was prepared in the same manner as in Example 2except that it was irradiated with ultraviolet light having a centralwavelength of 365 nm in an integrated dose of 5 mJ/cm². The cleaningsheet thus prepared was then measured for tensile modulus of cleaninglayer in the same manner as in Example 2. The results were 0.67 N/mm².The adhesive layer of the cleaning layer was then measured for adhesionwith respect to silicon wafer. The results were 0.33 N/10 mm.

[0070] It was tried to convey a conveying cleaning wafer prepared fromthe foregoing cleaning sheet in the same manner as in Example 2 throughthe interior of the substrate processing equipment having a wafer stagehaving 22,000 foreign matters attached thereto. As a result, theconveying cleaning wafer was fixed to the wafer stage. Thus, theconveying cleaning wafer could no longer be conveyed.

EXAMPLE 3

[0071] To 100 parts of an acrylic polymer (weight-average molecularweight: 700,000) obtained from a monomer mixture comprising 75 parts of2-ethylhexyl acrylate, 20 parts of methyl acrylate and 5 parts ofacrylic acid were added 50 parts of a polyethylene glycoldimethacrylate, 50 parts of urethane acrylate, 3 parts of benzyldimethyl ketal and 3 parts of diphenylmethane diisocyanate. The mixturewas then uniformly stirred to obtain a solution of an ultraviolet-curingadhesive.

[0072] Separately, an adhesive solution obtained in the same manner asmentioned above except that the foregoing adhesive was free of benzyldimethyl ketal was applied to one side of a polyester peelable filmhaving a thickness of 25 μm and a width of 250 mm to a dry thickness of10 μm to provide an ordinary adhesive layer thereon. A polyesterpeelable film having a thickness of 38 μm was then stuck to the surfaceof the ordinary adhesive layer. The foregoing ultraviolet-curingadhesive solution was applied to the other side of the base materialfilm to a dry thickness of 40 μm to provide an adhesive layer as acleaning layer thereon. A similar peelable film was then stuck to thesurface of the cleaning layer.

[0073] The resulting sheet was then irradiated with ultraviolet lighthaving a central wavelength of 365 nm in an integrated dose of 3,000mJ/cm² to obtain a cleaning sheet according to the invention. Thesurface of the cleaning layer had substantially no tackiness. Thecleaning layer which had been cured by ultraviolet light exhibited atensile modulus of 0.58 N/mm². The measurement of tensile modulus wascarried out by a testing method according to JIS K7127. The cleaninglayer was stuck to the mirror surface of a silicon wafer at a width of10 mm, and then measured for 180° peel adhesion with respect to siliconwafer according to JIS Z0237. The results were 0.0049 N/10 mm. It wasthus confirmed that the cleaning layer has substantially no tackiness.

[0074] The cleaning layer was measured for surface resistivity at atemperature of 23° C. and a relative humidity of 60% by means of a TypeMCP-UP450 surface resistivity meter produced by Mitsubishi ChemicalCorporation. As a result, the reading was greater than 9.99×10¹³ Ω/□,making the measurement impossible. It was thus confirmed that thecleaning layer has substantially no electrical conductivity.

[0075] The peelable film was then peeled off the cleaning sheet on theordinary adhesive layer side thereof. The cleaning sheet was then stuckto the back side (mirror surface) of an 8 inch silicon wafer to preparea conveying cleaning wafer with a cleaning function (1).

EXAMPLE 4

[0076] A polyester film having a thickness of 25 μm and a width of 250mm was used as a cleaning layer. The same ordinary adhesive layer asused in Example 3 was provided on one side of the polyester film to adry thickness of 10 μm. A polyester peelable film having a thickness of38 μm was then stuck to the surface of the ordinary adhesive layer toprepare a cleaning sheet.

[0077] The polyester film as a cleaning layer exhibited a tensilemodulus of 200 N/mm². The polyester film was also measured for 180° peeladhesion with respect to silicon wafer. The results were 0 N/10 mm. Itwas thus confirmed that the polyester film has substantially notackiness.

[0078] The polyester film was measured for surface resistivity. However,the reading was greater than 9.99×10¹³ Ω, making the measurementimpossible. From these results, it was confirmed that the cleaning layerhas substantially no electrical conductivity.

[0079] The peelable film was then peeled off the cleaning sheet. Acleaning wafer with a cleaning function (2) was then prepared in thesame manner as in Example 3.

[0080] Separately, three sheets of brand-new 8 inch silicon wafers weremeasured for the presence of foreign matters having a size of notsmaller than 0.2 μm on the mirror surface thereof by a laser typeforeign matter analyzer. As a result, foreign matters were found in anumber of 8 on the first sheet, 12 on the second sheet and 10 on thethird sheet. These wafers were then conveyed to the interior of separatesubstrate processing equipments with its mirror surface facing downward.Thereafter, these wafers were each measured for the presence of foreignmatters on the mirror surface thereof by means of a laser type foreignmatter analyzer. Foreign matters having a size of not smaller than 0.2μm were found on an 8 inch wafer size area in a number of 23,788 on thefirst silicon wafer, 26,008 on the second silicon wafer and 28,403 onthe third silicon wafer.

[0081] Subsequently, the peelable film was peeled off the foregoingconveying cleaning wafer (1) on the cleaning layer side thereof. Theconveying cleaning wafer (1) was then conveyed to the interior of thesubstrate processing equipment having the wafer stage having 23,788foreign matters attached thereto. As a result, the conveyance was madewith any troubles. Thereafter, the brand-new 8 inch silicon wafer having7 foreign matters having a size of not smaller than 0.2 μm presentthereon was conveyed to the interior of the substrate processingequipment with its mirror surface facing downward. These wafers werethen each measured for the presence of foreign matters having a size ofnot smaller than 0.2 μm by means of a laser type foreign matteranalyzer. As a result, foreign matters having a size of not smaller than0.2 μm were found on an 8 inch wafer size area in a number of 6,205,demonstrating that 74% of foreign matters which had been attached beforecleaning was removed.

[0082] Subsequently, the foregoing conveying cleaning wafer (2) was thenconveyed to the interior of the substrate processing equipment havingthe wafer stage having 26,008 foreign matters attached thereto. As aresult, the conveyance was made with any troubles. Thereafter, thebrand-new 8 inch silicon wafer having 13 foreign matters having a sizeof not smaller than 0.2 μm present thereon was subjected to measurementin the same manner as mentioned above. As a result, foreign mattershaving a size of not smaller than 0.2 μm were found on an 8 inch wafersize area in a number of 7,988, demonstrating that 69% of foreignmatters which had been attached before cleaning was removed.

COMPARATIVE EXAMPLE 3

[0083] The cleaning layer in a cleaning sheet prepared in the samemanner as in Example 3 except that it was irradiated with ultravioletlight having a central wavelength of 365 nm in an integrated dose of 5J/cm² had tackiness. The cleaning sheet thus prepared was then measuredfor tensile modulus of cleaning layer. The results were 0.067 N/mm². Thecleaning layer was then measured for adhesion with respect to siliconwafer. The results were 0.33 N/10 mm.

[0084] It was tried to convey a conveying cleaning wafer (3) preparedfrom the foregoing cleaning sheet in the same manner as in Example 3through the interior of the substrate processing equipment having awafer stage having 28,403 foreign matters attached thereto. As a result,the conveying cleaning wafer was fixed to the wafer stage. Thus, theconveying cleaning wafer could no longer be conveyed.

EXAMPLE 5

[0085] To 100 parts of an acrylic polymer (weight-average molecularweight: 2,800,000) obtained from a monomer mixture comprising 30 partsof 2-ethylhexyl acrylate, 70 parts of methyl acrylate and 10 parts ofacrylic acid were added 150 parts of dipentaerythritol hexaacrylate(trade name: UV 1700B, produced by Nippon Synthetic Chemical IndustryCo., Ltd.), 3 parts of a polyisocyanate compound (trade name: ColonateL, produced by Nippon Polyurethane Industry Co., Ltd.) and 10 parts ofbenzyl dimethyl ketal (Irgacure 651, produced by Ciba SpecialtyChemicals Co., Ltd.). The mixture was then uniformly stirred to obtainan ultraviolet-curing adhesive solution A. The ultraviolet-curingadhesive solution was then irradiated with ultraviolet light having acentral wavelength of 365 nm in an integrated dose of 1,000 mJ/cm² toundergo curing. The surface of the cleaning layer had substantially notackiness. The cleaning layer which had been cured with ultravioletlight exhibited a tensile modulus of 1,440 N/mm². The measurement oftensile was carried out by a testing method according to JIS K7127.

[0086] Separately, to 100 parts of an acrylic polymer (weight-averagemolecular weight: 700,000) obtained from a monomer mixture comprising 75parts of 2-ethylhexyl acrylate, 20 parts of methyl acrylate and 5 partsof acrylic acid were added 50 parts of a polyethylene glycol 200dimethacrylate (trade name: NK Ester 4G, produced by SninnakamuraChemical Co., Ltd.), 50 parts of urethane acrylate (trade name: U-N-01,produced by Sninnakamura Chemical Co., Ltd.) and 3 parts of apolyisocyanate compound (trade name: Colonate L, produced by NipponPolyurethane Industry Co., Ltd.). The mixture was then uniformly stirredto prepare a pressure-sensitive adhesive solution B.

[0087] The pressure-sensitive adhesive solution B was then applied toone side of a polyester base material film having a thickness of 25 μmand a width of 250 mm to a dry thickness of 10 μm to provide an ordinaryadhesive layer thereon. A polyester peelable film having a thickness of38 μm was then stuck to the surface of the ordinary adhesive layer.Subsequently, the foregoing ultraviolet-curing adhesive solution A wasapplied to the other side of the base material film to a dry thicknessof 10 μm to provide a cleaning layer thereon. A similar peelable filmwas then stuck to the surface of the cleaning layer.

[0088] The resulting sheet was then irradiated with ultraviolet lighthaving a central wavelength of 365 nm in an integrated dose of 1,000mJ/cm² to obtain a cleaning sheet according to the invention. Thepeelable film was then peeled off the cleaning sheet on the cleaninglayer side thereof. The cleaning layer was then measured for surfacefree energy. The results were 18.4 mJ/m². The cleaning layer exhibited acontact angle of 105.1 degrees with respect to water.

[0089] The peelable film was then peeled off the cleaning sheet on theordinary adhesive layer side thereof. The cleaning sheet was then stuckto the back side (mirror surface) of an 8 inch silicon wafer with a handroller to prepare a conveying cleaning wafer with a cleaning function.

[0090] Separately, the wafer stage was removed from the substrateprocessing equipment, and then measured for the presence of foreignmatters having a size of not smaller than 0.3 μm by a laser type foreignmatter analyzer. As a result, foreign matters having a size of notsmaller than 0.3 μm were found on an 8 inch wafer size area in a numberof 21,000.

[0091] Subsequently, the peelable film was peeled off the cleaning waferon the cleaning layer side thereof. The cleaning wafer was then conveyedto the interior of the substrate processing equipment. As a result, thecleaning layer didn't firmly adhere to the position to be cleaned evenafter 100 sheets of continuous conveyance. Thus, the conveyance was madewithout any troubles.

[0092] Thereafter, the wafer stage was removed from the substrateprocessing equipment, and then measured for the presence of foreignmatters having a size of not smaller than 0.3 μm by a laser type foreignmatter analyzer. As a result, foreign matters having a size of notsmaller than 0.3 μm were found on an 8 inch wafer size area in a numberof 10,000, demonstrating that half the foreign matters which had beenattached before cleaning was removed.

COMPARATIVE EXAMPLE 5

[0093] As an adhesive for cleaning layer there was used an adhesivesolution C prepared by a process which comprises adding 100 parts of apolyethylene glycol 200 dimethacrylate (trade name: NK Ester 4G,produced by Sninnakamura Chemical Co., Ltd.), 100 parts of apolyethylene glycol 600 diacrylate (trade name: NK Ester A-600, producedby Sninnakamura Chemical Co., Ltd.) and 3 parts of a polyisocyanatecompound (trade name: Colonate L, produced by Nippon PolyurethaneIndustry Co., Ltd.) to 100 parts of an acrylic polymer (weight-averagemolecular weight: 2,800,000) obtained from a monomer mixture comprising30 parts of 2-ethylhexyl acrylate, 70 parts of methyl acrylate and 10parts of acrylic acid, and then stirring uniformly the mixture. Thecleaning layer thus obtained was then measured for tensile modulus inthe same manner as in Example 5. The results were 0.1 N/mm².

[0094] A cleaning sheet was prepared from the cleaning layer in the samemanner as in Example 5. The cleaning layer was then measured for surfacefree energy. The results were 57.3 mJ/m². The cleaning layer exhibited acontact angle of 49.4 degrees with respect to water.

[0095] It was dried to convey a conveying cleaning wafer prepared fromthe foregoing cleaning sheet in the same manner as in Example 5 to theinterior of the substrate processing equipment. As a result, thecleaning wafer was fixed to the wafer stage during the conveyance of thefirst sheet. Thus, the conveying cleaning wafer could no longer beconveyed.

EXAMPLE 6

[0096] To 100 parts of an acrylic polymer (weight-average molecularweight: 700,000) obtained from a monomer mixture comprising 75 parts of2-ethylhexyl acrylate, 20 parts of methyl acrylate and 5 parts ofacrylic acid were added 100 parts of a polyethylene glycol 200dimethacrylate (trade name: NK Ester 4G, produced by SninnakamuraChemical Co., Ltd.), 3 parts of a polyisocyanate compound (trade name:Colonate L, produced by Nippon Polyurethane Industry Co., Ltd.) and 3parts of a benzyl dimethyl ketal (Irgacure 651, produced by CibaSpecialty Chemicals Co., Ltd.) as a photopolymerization initiator. Themixture was then uniformly stirred to prepare an ultraviolet-curingadhesive solution A.

[0097] Separately, an adhesive solution obtained in the same manner asmentioned above except that the foregoing adhesive solution A was freeof benzyl dimethyl ketal as a photopolymerization initiator was appliedto one side of a polyester peelable film having a thickness of 38 μm anda width of 250 mm to a dry thickness of 10 μm to provide an ordinaryadhesive layer thereon. A polyester peelable film having a thickness of38 μm was then stuck to the surface of the ordinary adhesive layer.Subsequently, the foregoing ultraviolet-curing adhesive solution A wasapplied to the other side of the base material film to a dry thicknessof 10 μm to provide an adhesive layer as a cleaning layer thereon. Asimilar peelable film was then stuck to the surface of the adhesivelayer.

[0098] The resulting sheet was then irradiated with ultraviolet lighthaving a central wavelength of 365 nm in an integrated dose of 2,000mJ/cm²to obtain a cleaning sheet according to the invention. Thepeelable film was then peeled off the cleaning sheet on the cleaninglayer side thereof. The cleaning sheet was then measured for Vickershardness of cleaning layer by means of a Type MHA-400 Vickers hardnessmeter produced by NEC. The results were 45.

[0099] The cleaning layer which had been cured with ultraviolet lightexhibited a tensile modulus of 147.2 N/mm². The measurement of tensilemodulus was carried out by a testing method according to JIS K7127. Thecleaning layer was stuck to the mirror surface of a silicon wafer at awidth of 10 mm, and then measured for 180° peel adhesion with respect tosilicon wafer according to JIS Z0237. The results were 0.0049 N/10 mm.It was thus confirmed that the cleaning layer has substantially notackiness.

[0100] The cleaning layer was measured for surface resistivity at atemperature of 23° C. and a relative humidity of 60% by means of a TypeMCP-UP450 surface resistivity meter produced by Mitsubishi ChemicalCorporation. As a result, the reading was greater than 9.99×10¹³ Ω/□,making the measurement impossible. From these results, it was confirmedthat the cleaning layer has substantially no electrical conductivity.

[0101] The peelable film was then peeled off the cleaning sheet. Thecleaning sheet was then stuck to the back side (mirror surface) of an 8inch silicon wafer to prepare a conveying cleaning wafer with a cleaningfunction.

[0102] Separately, two wafer stages were removed from a substrateprocessing equipment, and then measured for the presence of foreignmatters having a size of not smaller than 0.3 μm by means of a lasertype foreign matter analyzer. As a result, foreign matters having a sizeof not smaller than 0.3 μm were found on an area having an 8 inch wafersize in a number of 25,000 on one of the two wafer stages and 23,000 onthe other.

[0103] Subsequently, the peelable film was peeled off the foregoingconveying cleaning wafer on the cleaning layer side thereof. Theconveying cleaning wafer was then conveyed to the interior of thesubstrate processing equipment having the wafer stage having 25, 000foreign matters attached thereto. As a result, the conveyance of theconveying cleaning wafer was conducted without any troubles. Thereafter,the wafer stage was removed, and then measured for the presence offoreign matters having a size of not smaller than 0.3 μm by means of alaser type foreign matter analyzer. As a result, foreign matters havinga size of not smaller than 0.3 μm were found on an area having an 8 inchwafer size in a number of 4,800, demonstrating that ⅘ or more of theforeign matters which had been attached before cleaning had beenremoved.

COMPARATIVE EXAMPLE 6

[0104] A cleaning sheet was prepared in the same manner as in Example 6except that as an adhesive for cleaning layer there was used an adhesivesolution B prepared by a process which comprises adding 100 parts of apolyethylene glycol 600 diacrylate (trade name: NK Ester A-600, producedby Sninnakamura Chemical Co., Ltd.), 3 parts of a polyisocyanatecompound (trade name: Colonate L, produced by Nippon PolyurethaneIndustry Co., Ltd.) and 10 parts of benzyl dimethyl ketal (tradename:Irgacure 651, produced by Ciba Specialty Chemicals Co., Ltd.) as aphotopolymerization initiator to 100 parts of an acrylic polymer(weight-average molecular weight: 2,800,000) obtained from a monomermixture comprising 30 parts of 2-ethylhexyl acrylate, 70 parts of methylacrylate and 10 parts of acrylic acid, and then stirring uniformly themixture. The cleaning sheet thus prepared was then measured for Vickershardness of cleaning layer in the same manner as mentioned above. Theresults were 5. The cleaning layer was measured for surface free energy.The results were 34.6 mJ/cm². The cleaning layer exhibited a contactangle of 82.3 degrees with respect to water.

[0105] It was dried to convey a conveying cleaning wafer prepared fromthe foregoing cleaning sheet in the same manner as in Example 6 to theinterior of the substrate processing equipment having the wafer stagehaving 23,000 foreign matters attached thereto. As a result, thecleaning wafer was fixed to the wafer stage during the conveyance of thefirst sheet. Thus, the conveying cleaning wafer could no longer beconveyed.

EXAMPLE 7

[0106] To 100 parts of an acrylic polymer (weight-average molecularweight: 700,000) obtained from a monomer mixture comprising 75 parts of2-ethylhexyl acrylate, 20 parts of methyl acrylate and 5 parts ofacrylic acid were added 50 parts of a polyethylene glycol 200dimethacrylate (trade name: NK Ester 4G, produced by SninnakamuraChemical Co., Ltd.), 50 parts of urethane acrylate (trade name: U-N-01,produced by Sninnakamura Chemical Co., Ltd.), 3 parts of apolyisocyanate compound (trade name: Colonate L, produced by NipponPolyurethane Industry Co., Ltd.) and 3 parts of benzyldimethylketal as aphotopolymerization initiator. The mixture was then uniformly stirred toobtain an ultraviolet-curing adhesive solution A.

[0107] Separately, an adhesive solution obtained in the same manner asmentioned above except that the foregoing adhesive solution A was freeof benzyl dimethyl ketal as a photopolymerization initiator was appliedto one side of a polyester peelable film having a thickness of 38 μm anda width of 250 mm to a dry thickness of 10 μm to provide an ordinaryadhesive layer thereon. A polyester peelable film having a thickness of38 μm was then stuck to the surface of the ordinary adhesive layer.Subsequently, the foregoing ultraviolet-curing adhesive solution A wasapplied to the other side of the base material film to a dry thicknessof 10 μm to provide an adhesive layer as a cleaning layer thereon. Asimilar peelable film was then stuck to the surface of the adhesivelayer.

[0108] The resulting sheet was then irradiated with ultraviolet lighthaving a central wavelength of 365 nm in an integrated dose of 1,000mJ/cm² to obtain a cleaning sheet according to the invention. Thepeelable film was then peeled off the cleaning sheet on the cleaninglayer side thereof. The cleaning sheet which had been cured withultraviolet light exhibited a friction coefficient of 1.7 and a tensilemodulus of 50 N/mm². For the measurement of friction coefficient, astainless steel plate having a size of 50 mm×50 mm was allowed to movealong the surface of the cleaning layer in a predetermined direction ata rate of 300 mm/min at a vertical load of 9.8 N. The resultingfrictional resistance was then measured by a universal tensile testingmachine. The measurement of tensile modulus was conducted by a testingmethod according to JIS K7127.

[0109] The peelable film was then peeled off the cleaning sheet on theordinary adhesive layer side thereof. The cleaning sheet was then stuckto the back side (non-cleaning surface) of a contact pin cleaner (tradename: Passchip, produced by PASS INC.) as a contact pin cleaning memberhaving the shape of an 8 inch silicon wafer with a hand roller toprepare a conveying cleaning member for cleaning function.

[0110] Subsequently, the peelable film was peeled off the cleaningmember on the cleaning layer side thereof. The cleaning member was thendummy-conveyed through the interior of a wafer probe which is aconduction inspection equipment for the production of semiconductor toclean the contact pin and the chuck table. As a result, the cleaninglayer didn't firmly adhere to the contact position. Thus, the conveyancewas made without any troubles.

[0111] Thereafter, the contact pin was observed under microscope. As aresult, it was confirmed that foreign matters such as oxide which hadbeen attached to the contact pin before cleaning disappeared,demonstrating that the contact pin had been cleaned. Further, silicontailings having a size of about 1 mm which had been found on the chucktable before cleaning were found to disappear completely, demonstratingthat the chuck table was cleaned. Thereafter, wafers as products wereconveyed and inspected on an actual basis. As a result, processing wasmade without any problems.

EXAMPLE 8

[0112] To 100 parts of an acrylic polymer (weight-average molecularweight: 700,000) obtained from a monomer mixture comprising 75 parts of2-ethylhexyl acrylate, 20 parts of methyl acrylate and 5 parts ofacrylic acid were added 50 parts of a polyethylene glycol 200dimethacrylate (trade name: NK Ester 4G, produced by SninnakamuraChemical Co., Ltd.), 50 parts of urethane acrylate (trade name: U-N-01,produced by Sninnakamura Chemical Co., Ltd.), 3 parts of apolyisocyanate compound (trade name: Colonate L, produced by NipponPolyurethane Industry Co., Ltd.) and 3 parts of a benzyl dimethyl ketal(Irgacure 651, produced by Ciba Specialty Chemicals Co., Ltd.) as aphotopolymerization initiator. The mixture was then uniformly stirred toprepare an ultraviolet-curing adhesive solution A.

[0113] Separately, an ordinary pressure-sensitive adhesive solution Awas obtained in the same manner as mentioned above except that theforegoing adhesive was free of benzyl dimethyl ketanol.

[0114] The ordinary pressure-sensitive adhesive solution A was appliedto one side of a polyester base material film having a thickness of 25μm and a width of 250 mm to a dry thickness of 10 μm to provide anordinary adhesive layer. A polyester peelable film having a thickness of38 μm was then stuck to the surface of the ordinary adhesive layer. Theforegoing ultraviolet-curing adhesive solvent A was applied to the otherside of the base material film to a dry thickness of 30 μm to provide anadhesive layer as a cleaning layer. A similar peelable film was stuck tothe surface of the adhesive layer to prepare a cleaning sheet A.

[0115] The ultraviolet-curing adhesive A was then measured for tensilemodulus (testing method: JIS K7127). As a result, it exhibited a tensilemodulus of 0.1 N/mm² before it underwent curing reaction by ultravioletlight. The ultraviolet-curing adhesive A which had been irradiated withultraviolet light having a central wavelength of 365 nm in an integrateddose of 1,000 mJ/cm² exhibited a tensile modulus of 49 N/mm².

[0116] The cleaning sheet A thus obtained was then stuck to a wafer by adirect cutting type tape sticker (NEL-DR8500II, produced by NITTO SEIKIINC.). During this procedure, the sheet A was stuck to the back side(mirror surface) of an 8 inch silicon wafer, and then cut into the shapeof wafer by direct cutting process. This operation was continuouslyconducted over 25 sheets. As a result, no cutting wastes were producedduring sheet cutting.

[0117] Thereafter, 5 sheets of the wafers with sheet were irradiatedwith ultraviolet light having a central wavelength of 365 nm in anintegrated dose of 1,000 mJ/cm² to prepare a conveying cleaning wafer Awith a cleaning function.

[0118] Separately, 4 sheets of brand-new 8 inch silicon wafers were eachmeasured for the presence of foreign matters having a size of notsmaller than 0.2 μm on the mirror surface thereof by a laser typeforeign matter analyzer. As a result, foreign matters having a size ofnot smaller than 0.2 μm were found in a number of 8 on the first sheet,11 on the second sheet, 9 on the third sheet and 5 on the fourth sheet.These wafers were conveyed to the interior of separate substrateprocessing equipments having an electrostatic attraction mechanism withits mirror surface facing downward, and then measured for the presenceof foreign matters having a size of not smaller than 0.2 μm by a lasertype foreign matter analyzer. As a result, foreign matters having a sizeof not smaller than 0.2 μm were found on an 8 inch wafer size area in anumber of 31,254 on the first sheet, 29,954 on the second sheet, 28,683on the third sheet and 27,986 on the fourth sheet.

[0119] Subsequently, the peelable film was peeled off the foregoingconveying cleaning wafer A on the cleaning layer side thereof. Theconveying cleaning wafer A was then conveyed to the interior of thesubstrate processing equipment having the wafer stage having 31,254foreign matters attached thereto. As a result, the conveyance was madewithout any troubles. Thereafter, a brand-new 8 inch silicon wafer wasconveyed to the interior of the substrate processing equipment with itsmirror surface facing downward, and then measured for the presence offoreign matters having a size of not smaller than 0.2 μm by a laser typeforeign matter analyzer. This operation was conducted 5 times. Theresults are set forth in Table 1.

EXAMPLE 9

[0120] A cleaning sheet B was prepared in the same manner as in Example8 except that as an ultraviolet-curing adhesive there was used anultraviolet-curing adhesive solution B prepared by a process whichcomprises adding 100 parts of a polyfunctional urethane acrylate (tradename: UV 1700B, produced by Nippon Synthetic Chemical Industry Co.,Ltd.), 3 parts of a polyisocyanate compound (trade name: Colonate L,produced by Nippon Polyurethane Industry Co., Ltd.) and 10 parts ofbenzyl dimethyl ketal (trade name: Irgacure 651, produced by CibaSpecialty Chemicals Co., Ltd.) as a photopolymerization initiator to 100parts of an acrylic polymer (weight-average molecular weight: 2,800,000)obtained from a monomer mixture comprising 30 parts of 2-ethylhexylacrylate, 70 parts of methyl acrylate and 10 parts of acrylic acid, andthen stirring uniformly the mixture. The ultraviolet-curing adhesive Bwas then measured for tensile modulus. As a result, it exhibited atensile modulus of 0.01 N/mm² before it underwent curing. Theultraviolet-curing adhesive B which had been irradiated with ultravioletlight having a central wavelength of 365 nm in an integrated dose of1,000 mJ/cm² exhibited a tensile modulus of 1,440 N/mm².

[0121] The foregoing cleaning sheet B was then subjected to directcutting process in the same manner as in Example 8 to prepare 25 sheetsof wafers with sheet. As a result, no cuttings were produced duringsheet cutting. Five out of the 25 sheets of wafers were then irradiatedwith ultraviolet light having a central wavelength of 365 nm in anintegrated dose of 1,000 mJ/cm² to prepare a conveying cleaning wafer Bwith a cleaning function.

[0122] Subsequently, the peelable film was peeled off the foregoingconveying cleaning wafer B on the cleaning layer side thereof. Theconveying cleaning wafer B was then conveyed to the interior of thesubstrate processing equipment having the wafer stage having 29,954foreign matters attached thereto. As a result, the conveyance was madewithout any troubles. Thereafter, an 8 inch silicon wafer was conveyedto the interior of the substrate processing equipment with its mirrorsurface facing downward, and then measured for the presence of foreignmatters having a size of not smaller than 0.2 μm by a laser type foreignmatter analyzer. This operation was conducted 5 times. The results areset forth in Table 1.

COMPARATIVE EXAMPLE 8

[0123] A wafer with sheet was prepared by direct cutting process in thesame manner as in Example 8 except that a cleaning sheet C prepared by aprocess which comprises irradiating the cleaning sheet A withultraviolet light having a central wavelength of 365 nm in an integrateddose of 1,000 mJ/cm² before being stuck to the wafer. As a result, alarge amount of cutting wastes were produced from the cleaning layerduring sheet cutting. These cuttings were then much attached to the edgeof the wafer with sheet, the back side of the wafer and the tapesticker. Accordingly, the preparation of the wafer C with sheet wassuspended.

COMPARATIVE EXAMPLE 9

[0124] A cleaning sheet D was prepared in the same manner as in Example8 except that as an adhesive for cleaning layer there was used thepressure-sensitive adhesive solution A described in Example 8. Thecleaning layer in the cleaning sheet D exhibited a tensile modulus of0.1 N/mm².

[0125] The cleaning sheet D was then subjected to direct cutting in thesame manner as in Example 8 to prepare a wafer with sheet. As a result,no cutting wastes were produced during sheet cutting. 25 sheets ofwafers with sheet were prepared. It was then tried to convey theconveying cleaning wafer D to the interior of the substrate processingequipment having a wafer stage having 27,986 foreign matters attachedthereto. As a result, the conveying cleaning wafer D adhered to thewafer stage during the conveyance of the first sheet. Thus, the cleaningwafer D could no longer be conveyed. Percent removal of foreign matters1 sheet 2 sheets 3 sheets 4 sheets 5 sheets conveyed conveyed conveyedconveyed conveyed Example 8 85% 92% 96% 96% 96% Example 9 70% 75% 83%83% 83% Comparative The preparation of cleaning wafer was suspended.Example 8 Comparative Troubles Conveyance Conveyance ConveyanceConveyance Example 9 in suspended suspended suspended suspendedconveyance

[0126] Industrial Applicability

[0127] As mentioned above, the cleaning sheet according to the inventioncan certainly be conveyed through the interior of a substrate processingequipment as well as can simply and certainly remove foreign mattersattached to the interior of the equipment.

[0128] Although the invention has been described in its preferred formwith a certain degree of particularity, it is understood that thepresent disclosure of the preferred form can be changed in the detailsof construction and in the combination and arrangement of parts withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

1. A cleaning sheet comprising a cleaning layer having substantially notackiness and having a tensile modulus of not lower than 0.98 N/mm² asdetermined according to JIS K7127.
 2. A cleaning sheet according toclaim 1, further comprising a base material for supporting said cleaninglayer.
 3. A cleaning sheet according to claim 1, further comprising: abase material for supporting a cleaning layer on one side thereof; andan ordinary adhesive layer provided on the other side of said basematerial.
 4. A cleaning sheet according to claim 1, wherein saidcleaning layer exhibits a 180° peel adhesion of not higher than 0.20N/10 mm with respect to a mirror surface of silicon wafer.
 5. A cleaningsheet according to claim 1, wherein said cleaning layer hassubstantially no tackiness and substantially no electrical conductivity.6. A cleaning sheet according to claim 5, wherein said cleaning layerhaving substantially no tackiness and substantially no electricalconductivity is made of a plastic material or film.
 7. A cleaning sheetaccording to claim 1, wherein said cleaning layer exhibits a surfacefree energy of less than 30 mJ/m².
 8. A cleaning sheet according toclaim 7, wherein said cleaning layer exhibits a contact angle of greaterthan 90 degrees with respect to water.
 9. A cleaning sheet comprising acleaning layer having a Vickers hardness of not lower than
 10. 10. Acleaning sheet according to claim 9, further comprising a base materialfor supporting said cleaning layer.
 11. A cleaning sheet according toclaim 9, further comprising: a base material for supporting a cleaninglayer on one side thereof; and an ordinary adhesive layer provided onthe other side of said base material.
 12. A cleaning sheet according toany one of claims 1 and 9, wherein said cleaning layer comprises anadhesive layer and has been cured by an active energy.
 13. A cleaningsheet according to claim 12, wherein said cleaning layer is obtained bysubjecting a pressure-sensitive adhesive polymer containing at least acompound having one or more unsaturated double bonds per molecule and apolymerization initiator to polymerization curing reaction with anactive energy so that the tackiness thereof substantially disappears.14. A cleaning sheet according to claim 13, wherein said active energyis ultraviolet light.
 15. A conveying member with a cleaning functioncomprising a cleaning sheet according to any one of claims 3 and 11provided thereon with said ordinary adhesive layer.
 16. A method forcleaning a substrate processing equipment, comprising a step ofconveying any one of a cleaning sheet according to claim 1 and aconveying member with a cleaning function according to claim 15 to aninterior of the substrate processing equipment.
 17. A cleaning memberfor conduction inspection equipment comprising: a contact pin cleanerfor removing foreign matters attached to a conduction inspection contactpin of said conduction inspection equipment; and a cleaning sheetaccording to claim 1 provided on one side of said contact pin cleanerfor removing foreign matters attached to a contact area of an equipmentwith which said contact pin cleaner comes in contact.
 18. A cleaningmember for conduction inspection equipment comprising: a contact pincleaner provided on one side of a conveying member for removing foreignmatters attached to a conduction inspection contact pin of saidconduction inspection equipment; and a cleaning sheet according to claim1 provided on one side of said contact pin cleaner for removing foreignmatters attached to a contact area of an equipment with which saidcontact pin cleaner comes in contact.
 19. A cleaning member according toany one of claims 17 and 18, wherein said cleaning sheet comprises anadhesive layer provided on one side of a base material and a cleaninglayer provided on the other for removing foreign matters attached to thecontact area of an equipment with which said contact pin cleaner comesin contact.
 20. A cleaning sheet according to claim 1, wherein saidcleaning layer exhibits a friction coefficient of not lower than 1.0.21. A cleaning sheet according to claim 1, wherein said cleaning layerhas substantially no tackiness and a tensile modulus of not higher than2,000 N/mm² as determined according to JIS K7127.
 22. A method forcleaning a conduction inspection equipment, comprising a step ofconveying a cleaning member according to any one of claims 17, 18 and 19to an interior of said conduction inspection equipment.
 23. A processfor preparing a conveying member with a cleaning function, comprisingsteps of: laminating a cleaning sheet having a cleaning layer made of anadhesive which undergoes polymerization curing when acted upon by anactive energy provided on one side of a base material and an ordinaryadhesive layer-provided on the other with a conveying member with anordinary adhesive layer interposed therebetween in such an arrangementthat the shape of said cleaning sheet is greater than that of saidconveying member; and cutting said cleaning sheet along the profile ofsaid conveying member; wherein said cleaning layer undergoespolymerization curing reaction after the cutting of said cleaning sheetalong the profile of said conveying member.
 24. A process for preparinga conveying member with a cleaning function according to claim 23,wherein said cleaning layer exhibits a tensile modulus of not higherthan 1 N/mm² at the time of sheet cutting as determined according to JISK7127.
 25. A process for preparing a conveying member with a cleaningfunction according to claim 23, wherein said cleaning layer exhibits atensile modulus of not lower than 10 N/mm² after polymerization curingas determined according to JIS K7127.
 26. A cleaning sheet for use inthe process for the preparation of a conveying member with a cleaningfunction according to claim 23 comprising a cleaning layer made of anadhesive which can undergo polymerization curing when acted upon by anactive energy provided on one side of a base material and an ordinaryadhesive layer provided on the other, said cleaning layer being inuncured state.